Wax cup and handle for investment casting



Sept. 17, 1968 A. ROSENFELD 3,401,737

WAX CUP AND HANDLE FOR INVESTMENT CASTING Filed April 26, 1965 LLL FIQ. 1.

FIG. 2.

INVENTOR.

ARTHUR Rosa/#2211;

5) ms Arroe/vsrs HA RR/s, M501, RUSSELL &/(5Q/v United States Patent ABSTRACT OF THE DISCLOSURE A wax pattern to be used in investment casting comprising a cup-shaped wax base which is internally threaded to receive an externally threaded handle.

BACKGROUND OF THE INVENTION The present invention relates in general to investment casting and, more particularly, to improved means for supporting a wax pattern or pattern assembly while performing various operations thereon, such as enveloping it in a shell mold, for example.

A wax pattern or pattern assembly to be used in investment casting is normally mounted on a cup-shaped wax base, customarily referred to as a wax cup, which serves to support the pattern or pattern assembly. After a mold, such as a shell mold, has been formed around the wax cup and pattern assembly, and the wax has been melted out, the molten metal to be used in the casting operation may be poured into the cup-shaped cavity formed by the wax cup.

Heretofore, it has been conventional practice to mold into the end wall of each wax cup a stud onto which a handle can be threaded for use in supporting the wax cup, and any pattern or pattern assembly thereon, during various operations to be performed, such as forming a mold around the wax cup and pattern assembly.

The use of such a supporting stud cast into the end wall of the wax cup has various disadvantages. For example, it adds to the cost of making the wax cup by requiring an extra part and by requiring an extra operation in the manufacture of the cup. Also, casting a supporting stud into the wax cup in this manner results in undesirable stress concentrations within the end wall of the cup.

SUMMARY AND OBJECTS OF THE INVENTION A primary object of the invention is to overcome the foregoing and various other disadvantages of prior practice by directly connecting a supporting handle for the wax cup to the inner peripheral wall of the cup.

More particularly, a primary object is to connect the handle directly to the inner peripheral wall of the cup over a large portion of the area of such wall so as to distribute the load throughout a substantial portion of the structure of the cup and thus avoid stress concentrations.

Still more particularly, an important object of the invention is to provide means on the handle in threaded engagement with the inner peripheral wall of the wax cup for securing the :cup to the handle.

Still another object of the invention is to provide a device for supporting a wax pattern, comprising: a wax cup adapted to have the wax pattern mounted thereon; a tapered thread on the inner peripheral wall of the cup; a handle; and a tapered thread carried by the handle and engageable with the tapered thread on the inner peripheral wall of the cup.

Another important object of the invention is to provide a wax cup for use in investment casting having a tapered thread on its inner peripheral wall.

A further object is to provide a wax-pattern base for use in investment casting, comprising a wax member pro- 3,401,737 Patented Sept. 17, 1968 ice 2 vided with an internally threaded, tapered socket for the reception of an externally threaded, tapered handle.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the investment casting art in the light of this disclosure, may be achieved with the exemplary embodiments of the invention described in detail hereinafter and illustrated in the accompanying drawing.

DESCRIPTION OF THE DRAWING FIG. 1 is a semidiagrammatic elevational view of a device of the invention for supporting a wax pattern or pattern assembly;

FIG. 2 is an enlarged, sectional view taken as indicated by the arrowed line 2-2 of FIG. 1;

FIG. 3 is an isometric view showing a wax-pattern base or wax cup of the invention; and

FIGS. 4, 5 and 6 are elevational views showing alternative wax-cup handles of the invention, FIGS. 4- and 6 being fragmentary views.

DETAILED DESCRIPTION OF THE INVENTION to FIG. 1 of the drawing, diagrammatically illustrated therein is a wax pattern or pattern assembly 10 mounted on a wax cup 12 of the invention. The wax pattern or pattern assembly 10 may be a single pattern, or it may be a tree carrying two or more individual patterns. The exact configuration of the wax pattern or pattern assembly 10 forms no part of the present invention and it is therefore shown diagrammatically only. The wax pattern or pattern assembly 10 is mounted on the smaller end of the wax cup 12 in the usual manner.

The wax cup 12, as best shown in FIGS. 2 and 3, is of more-or-less conventional configuration. More particularly, the wax cup 12 is generally frusto-conical in shape, being closed at its smaller end 14 and open at its larger end 16. The latter is encircled by an annular flange 18 reinforced by external longitudinal ribs 20.

The inner peripheral wall 22 of the wax cup 12 forms a tapered socket 24 converging from the larger end 16 of the cup to the smaller end 14 thereof. Formed integrally with the inner peripheral wall 22 of the wax cup 12 is a coarse tapered thread 26- which occupies a substantial portion of the axial length of the inner peripheral wall 22.

The invention includes a handle 28 for supporting the wax cup 112 and the wax pattern or pattern assembly 10 as various operations are performed thereon, such as enveloping the wax pattern and cup in a shell mold, for example, not shown. The handle 28 includes a coarse, tapered thread 30 complementary to and engageable with the tapered thread 26 on the inner peripheral wall 22 of the wax cup 12.

With the foregoing construction, the wax cup 12 is secured to the handle 28 simply by screwing the thread 30 on the handle into the thread 26 in the cup, or by screwing the thread in the cup onto the thread on the handle. Since the threads 26 and 30 are relatively coarse, the threaded connection can be made and broken very quickly.

Directly threadedly connecting the handle 28 to the wax cup 12 in the foregoing manner eliminates the expense of incorporating a separate stud, not shown, in the end wall 14 of the wax cup 12. Also, the threads 26' and 30 distribute the loads transmitted between the wax cup 12 and the handle 28 over a relatively large area to avoid stress concentrations.

In the particular construction illustrated, the handle 28 is merely a tube 32 having a coil of round wire 34 welded to one end thereof to form the tapered thread 30. The

Referring initially tube 32 is provided with an opening 36 therethrough adjacent its other end for the reception of a hook, or the like, not shown, for suspending the handle 28, with the wax cup 12 and the wax pattern or pattern assembly thereon, from a conveyor, or the like, not shown.

FIG. 4 shows, fragmentan'ly, a handle 40 which is similar to the handle 28, except that it comprises a rod 42 having a coil of wire 44 welded thereonto to form a coarse, tapered thread 46 similar to the thread 30.

In FIG. 5 is shown a handle 50 having the form of a rod 52 provided with a hook 54 at one end and having welded to its other end a coil of Wire 56 forming a coarse,

tapered thread 58. The axis of the by the broken line 60'.

FIG. 6 illustrates another handle of the invention provided with an integral tapered thread 72 which may be formed by machining, casting, or the like.

Although exemplary embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims which follow.

I claim as my invention:

1. In combination: a frusto-coni-cal meltable wax cup for investment casting, formed solely of meltable wax and defining an internal cavity of frusto-conical shape, the large end being open to provide free access to the tapered thread 58 is designated interior thereof; the inner surface of the tapered side wall of said cup being provided with formations defining a coarse tapered threaded portion; and an elongated handle means having one end thereof extending loosely into said cup, through said open end, said handle means being provided With a conical thread formation at said one end loosely threadedly engaging said threaded portion of said cup.

2. A device as defined in claim 1 wherein said elongated handle means comprises a straight cylindrical portion at said one end, said conical thread formation comprising a helically arranged metal strand surrounding and secured at its ends to said one end portion of said handle.

References Cited UNITED STATES PATENTS 802,383 10/1905 Fenn 215-43 2,099,454 11/1937 Siqveland 3217 2,994,931 8/1961 ,Operhall et al. 22162 3,062,568 11/1962 Andresen et a1 287117 3,297,187 1/1967 Thiesen 21543 FOREIGN PATENTS 209,576 7/ 1957' Australia.

I. SPENCER OVERHOLSER, Primary Examiner. ROBERT D. BALDWIN, Assistant Examiner. 

